Welcome to the Piano World Piano ForumsOver 2 million posts about pianos, digital pianos, and all types of keyboard instruments
Join the World's Largest Community of Piano Lovers
(it's free)
It's Fun to Play the Piano ... Please Pass It On!

I am having a room added to my house which will contain, initially, my upright and perhaps later a 6/7 ft grand. The room will have a wooden floor and I am given to understand that a normal wooden floor is designed to take a deadload of 1.5 kN/m² (kN is kilo Newtons) I have no clear idea of what this means. Does anybody happen to know how many kN/m² might be exerted by a grand of this size?

Good evening Withindale, I hope that the weather in Suffolk is not as foul as that affecting SW France today. I have to admit that in technical matters I am a complete dunce and that despite your erudite response I am still not clear whether or not a floor specified at 1.5kN/m² is sufficiently strong to support a grand piano. Any further help that you can give will be much appreciated.

Indeed the sun shone on Suffolk today. I've heard it said that if you and I can walk across the room the floor will take a piano. My first post was going to ask how many people might be in the room at a party and how much would they weigh, but I left it out in case someone took offence.

Hello Jean Claude, put very simply, a 6/7 ft grand roughly needs 4 square meters of space (since 1 m = 3 ft, then the length and width of the piano implies 2 m for both dimensions). So we can divide its approximate mass of 500 kg by 4, which gives (roughly) 125 kg pushing on each of those square meters, so no problem. It's actually more complicated than that, as of course a grand has only three legs, not to mention the additional weight of the surrounding bench, pianist sitting, and especially other heavy furniture around if any.

I say if your new room is built according to construction specs, you will be just fine. It would be another story in an older house like mine where the joists are not so solid, or if there will be several other very heavy objects close to the piano like an enormous 6 ft tall bookcase, etc.

Picture three people (in the case of a typical grand), holding hands at arms' length, each standing on one heel, where the heels are little bit narrower than cuban heels but not quite as narrow as a stiletto heel, and where said people mass somewhere between well-built and obsese. If you reckon your floor could handle that, then it will probably handle a piano.

Marty's answer is most correct.The load limit will not be exceeded on a distributed basis (considering the large area the piano covers), but will certainly be exceed just considering the area under the wheels or caster cups, so that needs to be clarified with your builder.

Thank you all for your reassuring responses. I must say in passing that if a piano weighs about 500kg then each of our hand-holding party-goers will weigh, on average, just short of 170kg (for those of you who do not yet benefit from the Napoleonic system of weights, that is about 26 stones) I earnestly hope that they will not take it into their heads to start any sort of one-legged dance, not because of any concerns for the integrity of my floor but purely on aesthetic grounds.

Reinforce the floor if you are really worried. When we built our addition, I had the builder put double the I beams under the section of the room where we would put the piano, and double thickness plywood. My 7' M & H is about as heavy as most other brands' 9 footers.

... upright and perhaps later a 6/7 ft grand. The room will have a wooden floor and I am given to understand that a normal wooden floor is designed to take a deadload of 1.5 kN/m² (kN is kilo Newtons) I have no clear idea of what this means. Does anybody happen to know how many kN/m² might be exerted by a grand of this size?

I am not a construction engineer so the following is strictly a simplistic novice application of Physics to the complex computations of Load Distribution. It may help you explain your concerns to the engineer and ask him/her to provide you with a convincing design that mitigates your concern.

1 Newton (N) is 0.101972 kgf. Kilo (k) = 1000.

1.5 kN/m-2 = 1.5 x 1000 x 0.101972 kgf / m-2 = 152.96 kgf / m-2.

Let us assume that the 152.96 kgf is distributed evenly over 1 square meter, then we have approx. 0.0153 kgf / cm-2.

Let us now apply this to a hypothetical piano:

1. Steinway Model B, 211 cm, 345 kg (kgf). 2. Length is 211cm, width is 148cm. 3. Approx. area is 31228 cm-2 or 3.12 m-2 (square meters).4. Given shape of a grand, it is possible this area is evenly distributed under each foot.

Let us assume, simplistically, that the piano's weight is distributed to three legs evenly; then, each leg of the Model B will exert 115 kgf down through the wheel to the floor.

Exactly how this load is distributed by Building Engineering is beyond my expertise.

If this force is evenly distributed to a square meter, then the the floor deadload specification of 152.96 kgf / m-2 is larger than the piano load of 115-kgf / m-2.

For the sake of this discussion, let us further assume, simplistically, that the contact surface of the wheel is 5mm wide by 10 cm long yielding a contact surface area of 5 square centimeter (cm-2).

This means we have a theoretical 115-kgf down through 5 cm-2 of contact surface, or 23 kgf / cm-2.

Each contact point of the Model D is exerting a deadload force of 23 kgf / cm-2 on the floor.

If this force is not evenly distributed to a square meter, then the piano load of 23 kgf / cm-2 is much much larger than the floor deadload specification of 0.0153 kgf / cm-2.

Again, exactly how this load is distributed by Building Engineering is beyond my expertise. Hopefully, this can help you start a conversation with the Building Engineer.

Forgive me but just like in piano, the experts often have "little patience" with the perceived novice and they often wave us off too soon. It pays to listen to us.

In our case, a very good contractor ignored our specifications about an in-home IT room. It is a real IT room with real IT wiring, cooling and fire-suppresant requirements, but he ignored all our questions and waved us off.

I finally withheld the first payment before design commenced and wouldn't give him the signed contract until he listened and answered our questions; however stupid they might be in his eyes.

He then said that he thought we were just talking about a couple of computers sitting on a desk. The design for that would have been trivial compared to our actual needs.

I think the consumer needs to be as INFORMED as possible. This is true in piano shopping and also true in home construction and everything else.

Greetings, Wait a minute. Steinway pianos weigh about 50 kg. per foot, from the smallest to the largest. Big uprights can go as high as 340 Kg, but that is a really big, old upright. You are talking about 500 Kg pianos? A Steinway D weighs 450 kg. so if you are considering a pair of them, you will need to support a ton. This is the equivalent of, say, 15 people having a party. Seven couples dancing, with maybe a couple of dogs and kids scattered around...

I have never heard of a piano causing a structural problem in a building, but I am sure it has happened when a confluence of factors combine,(light framing, big pianos, termites, frat party, etc). Regards,

I am having a room added to my house which will contain, initially, my upright and perhaps later a 6/7 ft grand. The room will have a wooden floor and I am given to understand that a normal wooden floor is designed to take a deadload of 1.5 kN/m² (kN is kilo Newtons) I have no clear idea of what this means. Does anybody happen to know how many kN/m² might be exerted by a grand of this size?

You should be fine.

A 6'11 Steinway B has a distributed load of around 1.0 kN/m2 and a "point load" of 1.1 kN/m2, well within the limits.

Also, 1.5 kN/m² is not the maximum load of the wooden floor; rather, it is the minimum distributed load required by regulations (building code) for the support structures beneath the floor. Modern construction are engineered with additional safety margins so the structure will actually be able to take quite a bit more than this minimum requirement.

I have a lot of experience in moving and locating seriously heavy items. A grand weighs about 500 Kg. I weigh 80 Kg. So it is the equivalent of 6 medium sized adult males. If your floor won't stand that spread over the area of a 9' grand then you are in trouble even just using the room! Think of the weight of a row of full filing cabinets for example.

The second consideration is whether a caster will punch through a floor. Frankly it just shouldn't. If, however, this is likely to cause a problem use a big piano caster cup which will greatly distribute the weight. Also position the instrument, as far as possible so the the legs are over beams. (Look for the line of nail heads). That will be enough but if you are still worried use a piece of 3mm steel plate about the size of a sheet of A4, which you can spray paint to match your caster cups, under the cups. This will further reduce the pressure.

"Dad, do you know the piano is on my toe?" "You sing it, son, and I will play it".